Isaac Physics 'Road Collision' Problem

https://isaacphysics.org/questions/r...6-977abf64c5eb

I first found the deceleration of the two cars when they move as one body until stationary, which was a= -6.867ms^-2 (negative as am considering it acceleration rather than deceleration as easier to remember). Next I found the initial velocity the two cars, moving as one body, were travelling at, which gave u (given variable letter v)=25.1ms^-2.

After this I tried to work back to find u1 (velocity 1500kg was travelling at prior to the collision), tried a few things, however nothing seemed to give the correct answer. I looked at Tip 1, where one of the linked concepts was resolving vectors, and I see how this could be done, but don't see the use in it?

Could someone explain the next step I must take, and how the use of resolving the two possible vectors could be useful?

Did you get it solved?

Can you upload / enter your working so it's easier to read?

Initially I experienced a similar issue solving this problem, but the key to cracking it is to consider the components of the final momentum. You have the correct value for the velocity of the two vehicles after the collision so can easily work out its momentum by multiplying by 4000 (their total mass, modelling them as a single particle). Think about the direction it is moving in and hence split the momentum into horizontal and vertical components, considering conservation of momentum and the angle of collision to find the momentum of the cars before the collision and hence their velocities.
I hope this helps and makes sense! I may have explained this poorly as we haven't yet covered momentum in physics, so if you require any further clarification, let me know

Thank you that was really helpful! I just went back to the question now and I've got the answer, I just needed that hint on momentum you gave me!